Financial Instruments (Schedule Of Changes In Fair Value Of Level 3 Financial Assets) (Details) (USD $) In Thousands, unless otherwise specified								12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Fair Value Inputs Level 1 [Member]	Dec. 31, 2010 Fair Value Inputs Level 1 [Member]	Dec. 31, 2011 Fair Value Inputs Level 2 [Member]	Dec. 31, 2010 Fair Value Inputs Level 2 [Member]	Dec. 31, 2010 Fair Value Inputs Level 3 [Member]	Dec. 31, 2010 Fair Value Inputs Level 3 [Member] Long-Term Auction Rate Securities [Member]	Dec. 31, 2010 Fair Value Inputs Level 3 [Member] Long-Term UBS Put [Member]
Fair Value Of Assets And Liabilities Measured On A Recurring Basis [Line Items]
Balance at beginning of period	$ 593,402	$ 934,207	$ 419,020	$ 385,595	$ 174,382	$ 548,612		$ 23,649	$ 2,830
Sale of auction rate securities and exercise of UBS Put								(23,849)	(2,687)
Change in unrealized gain included in earnings								200
Change in unrealized loss included in earnings									(143)
Balance at end of period	$ 593,402	$ 934,207	$ 419,020	$ 385,595	$ 174,382	$ 548,612